1. Field of the Invention
The present invention relates to a four-way valve to be used mainly for switching the cooling and heating modes of an air conditioner.
2. Description of the Prior Art
In the refrigerating cycle of the air conditioner, there has been used the four-way valve for switching the direction of flow of a cooling medium for the cooling and heating operations. As the four-way valve of this kind, a mechanism shown in FIG. 6 has been proposed by Japanese Utility Model Laid-Open No. 54-165324 or Japanese- Patent Laid-Open No. 61-6468.
According to this proposal, there is connected to a valve body 1 an inlet passage 2 which leads to the discharge port of a compressor A. To the opposite side of the valve body 1, there are connected an output passage 3 leading to the suction port of the compressor A; a first passage 4 leading to an outdoor heat exchanger E.sub.1 ; and a second passage 5 leading to an indoor heat exchanger E.sub.2. In the valve body 1, there is fitted a bowl-shaped valve member 6 which is arranged slidably on a valve seat 8 opening the aforementioned three passages 3, 4 and 5 therein. The valve member 6 has its two sides connected to pistons 7a and 7b which have orifices 7c. These pistons 7a and 7b define, at the two end portions of the valve body 1, two chambers which have communication with the two side portion of a central valve seat 10a of a pilot valve member 10 by way of pilot tubes 9a and 9b. The outlet passage 3 has communication with the central portion of the valve seat 10a by way of another pilot tube 9c. In the valve member 10, there is fitted a pilot valve 10b which is actuated by an electromagnet M.
FIG. 6 shows the state of the cooling mode, in which communication is established between the pilot tubes 9b and 9c to drop pressure in the lefthand end portion of the valve body 1 so that the valve member 6 is moved to the left. In this state, the gases emanating under a high pressure from the compressor A are introduced from the inlet passage 2 to flow via the first passage 4, the outdoor heat exchanger E.sub.1, a capillary tube C and the indoor heat exchanger E.sub.2 until they are returned from the second passage 5 to the compressor A via the internal passage of the valve member 6 and the outlet passage 3.
If, in this state, the coil of the electromagnet M is energized, the pilot valve 10b is moved to the right to close the lefthand pilot tube 9b. Simultaneously with this, the central pilot tube 9c leading to the outlet pipe 3 communicates with the righthand tube 9a so that the lefthand end chamber of the valve body 1 takes a higher pressure than that of the righthand end chamber to move the valve member 6 to the right. As a result, the circuit is switched to the heating mode in which the inlet passage 2 communicates with the second passage 5 and in which the outlet passage 3 communicates with the first passage 4. If, on the other hand, the power supply to the coil is interrupted, the circuit restores the cooling mode of FIG. 6.
The four-way valve of the prior art thus far described is constructed of the main valve member for switching the circuit and the pilot valve member for actuating the main valve member and requires the piping connecting the two valve member. Moreover, the main valve member is of the reciprocating type having the paired pistons so that its construction is complicated with the increased number of parts and encountered by troubles when assembled. For the operations in the heating mode in window, still moreover, the power has to be supplied for maintaining the pilot valve so that the four-way valve of the prior art is uneconomically accompanied by much power consumption.